A work machine such as an agricultural tractor may be driven with motive force taking several forms such as a rear wheel drive, four wheel drive (4WD), mechanical front wheel drive (MFWD), endless track drive and others. In the case of an MFWD equipped tractor, the front wheel drive is typically not full time and an electronic switch in the operator station is used to switch between rear wheel drive and MFWD mode.
A work machine incorporating such a transmission is powered by a prime mover, usually consisting of a compression ignition or diesel engine. Such engine operates over a range of engine rpm's but has certain operating conditions in which the torque output and fuel efficiency are at a high level. The purpose of the transmission in such a work machine is to match ground speed to the optimal engine operating conditions so as to provide fuel efficient and effective operation.
Such work machines have a condition where the vehicle is required to move forward along the ground at a velocity substantially lower than the normal operational velocity of the vehicle. To accomplish this purpose, creeper gear arrangements may be provided in transmissions for work vehicles. These creeper gear arrangements may be a single speed or multiple speed arrangement. In prior art transmissions the creeper gear has been incorporated before or after the speed ratio gears or may function as a separate range. Typically, these designs add between approximately 50 millimeters and 75 millimeters of overall length to the transmission. With such a significant increase in length, the vehicle envelope is affected in a way that works against a compact work vehicle arrangement.
What is needed therefore in the art is a compact creeper gear arrangement for a transmission in a work vehicle.